Occasional musings on a variety of things.

Life on Earth

Ian Wishart has kindly responded to my recent post on chapter four of his book The Divinity Code. Rather than create a bulky ongoing commentfest, I prefer to post further articles (mainly because Blogger’s comment system combined with my layout equals shit).

One of my criticisms was that Ian’s application of the anthropic principle assumed that earth life is the only kind of life. At least, that is the premise that would have to be added to make the reasoning sound. I made a separate criticism that his argument assumed that life is special enough to demand more explanation than any other kind of physical phenomena. While I made the points separately, they can be made together. Here is Ian’s argument.

1. Life requires exactly earth-like conditions to arise.2. The chances of earth-like conditions arising are impossibly small.3. Therefore it is unreasonable to believe it happened by chance.4. Therefore it was done on purpose.5. Therefore God.

I suggested that there was an implicit assumption that earth life was the only kind of possible life – or else the first premise is false. If earth life is not the only kind of possible life, then the first premise becomes “earth life requires exactly earth-like conditions”, which is tautologous and therefore true, but invalidates the argument. To illustrate this, I made an analogous argument:

1. Ryan requires exactly Ryan’s Life conditions to arise.2. The chances of Ryan’s Life conditions arising are impossibly small.3. Therefore it is unreasonable to believe it happened by chance.4. Therefore it was done on purpose.5. Therefore God.

The Ryan argument seems obviously silly, because the chances of anyone else’s life being just right for them to arise is just as unlikely as Ryan’s life. The earth-life argument seems less silly because while we’re familiar with the idea of other potential people, we’re less familiar with the idea of other potential forms of life.

We know from everyday experience that there are millions of people who could correctly think, “Fucking hell, if Mum and Dad hadn’t had that last oyster 27 years ago, I wouldn’t be here!” It requires more thought to imagine the possibility of other potential kinds of life which could reflect on their existence and say, “Fucking hell, if we didn’t orbit a binary star system, we wouldn’t be here!”

Ian has recently been given a similar response, where someone has replaced “earth life” with “Cambridge cosmologists”. Ian quotes their counter-example:

1. If an all-powerful god made the world so that Cambridge Cosmologists would thrive, then Cambridge Cosmologists would thrive2. Arguably Cambridge Cosmologists do thrive3. Conclusion: An all-powerful god made the world so that Cambridge Cosmologists would thrive.

His respondent adds, “The problem with this argument is that Cambridge Cosmologists can be replaced with anything (including yours truly or tape-worms) and therefore is vacuous.”

It’s worth noting here that this is not really the argument that Ian was putting forth in chapter four. There is nothing like the first premise (“If God made the world so that Cambridge cosmologists would thrive, then they would”) in his argument.

Ian’s response is thus:

Your context is set too vaguely. If Cambridge Cosmologists, and only Cambridge Cosmologists, appeared to exist, this would be a closer analogy to the situation we currently find ourselves in…

It’s not an entirely adequate response to Mr Cambridge, but I’m not going to go into that, because Mr Cambridge’s email was not an entirely adequate response to Mr Wishart.

What it shows, though, is that I need to be more clear in my Ryan’s Life analogy. Presumably, what Ian is saying to me by quoting his response to Mr Cambridge is that my analogy would only be analogous if I was in fact the only person to exist. That’s fair enough, given how difficult an analogy it was. I’ll make it a bit clearer.

Ryan = earth-life.Ryan’s Life = the conditions on earth that give rise to earth-life.Other people = other potential forms of life.Other people’s lives = other potential lives that give rise to non-Ryan people.

The surprise that I am Ryan and not someone else is analogous to the surprise that earth-life exists and is not some other kind of life. It is analogous not because Ryan is the only person who exists, but because Ryan is the only person who is Ryan, amongst others who are not. The difference is that we can see other people, other potential lives, but we cannot see other potential forms of life. That was, in fact, my whole point – that this is why it’s intuitively compelling to believe that earth-life is unbelievably special, whereas it’s not intuitively compelling to believe that Ryan is unbelievably special. Because we have examples of alternatives to Ryan, but no examples of alternatives to earth-life.

This isn’t lost on Ian, and he’s provided a few arguments that, in fact, earth-life is the only possible kind of life. Biochemists have suggested that only carbon or silicon has the versatility and stability to be a basis for life, and carbon moreso than silicon. That narrows “life” down to “carbon-based life”. A fair enough argument. The problem is that carbon is fairly prevalent in the universe, and we don’t really know what other potential self-replicating patterns of matter could arise involving it.

We can speak of the unlikelihood of an entire cell forming spontaneously. We can speak of the lower unlikelihood of RNA forming spontaneously. We can speak of self-catalysing molecules – some of which we have produced. But we don’t have comprehensive knowledge of every possible self-replicating molecule and the chances of it forming spontaneously in conditions earth-like or not. We really don’t know the odds, though we do know that there’s an awful lot of time and an awful lot of space for them to play out. In other words, we have no reason to conclude that exactly earth’s conditions are required for carbon-based life to arise – still only the tautology that exactly earth’s conditions are required for exactly earth’s carbon-based life to arise.

Those paying close attention will note another analogy here. There’s no end to my statement, “We don’t know all the possible arrangements of matter and their likelihood of spontaneously occurring.” We can never know. Isn’t that analogous to the God of the Gap of the Origin of Life? A “Get Out of Argument Free” card?

Well, perhaps, and I suspect that’s the attitude of many scientists. “We don’t have a definite naturalistic explanation for the origin of life on earth, therefore there is a naturalistic explanation for the origin of life on earth that we don’t know.” It’s not even worth throwing “yet” on the end of the statement, because we can never know for sure, as I mentioned earlier.

Again, we’re back to the odds. Scientists assume there is a naturalistic explanation for life on earth – either one they’ve imagined already or one that have not – because there always has been in the past. Schizophrenia is not caused by demons. Palsy is not caused by fairies. Lightning is not caused by gods. Rainbows are not placed there by God. Mental states are not souls, but directly alterable chemical processes. Almost everything in the past that was previously given a supernatural explanation now has a proven naturalistic one. What are the odds that this one is different?

Let’s say you line up a thousand people, and you ask each one, “Have you ever lied?” Each one tells you they haven’t. Then you come back with a lie detector and ask them all again, “Have you ever lied?” The first 999 were lying, but when you get to the last guy, it turns out he died earlier that day. You can’t test him with the lie detector.

What do you believe about him? That he was the one guy in a thousand who actually had never lied? Do you believe neither that he had ever lied nor that he had? Or do you believe that he was the one guy in 1000 who had never lied, because some people are telling you so, and it’s just dumb luck you can’t prove for sure that he lied?

That’s the reason for the “faith” in naturalistic explanations of the origin of life. It’s a habit born from centuries of experience. It’s just unrealistically unlikely that this is the time that supernatural explanations trump naturalistic ones, after the last thousand examples of naturalistic explanations trumping supernatural ones.

But I digress. Back to the matter at hand. I claim we can’t know the odds of life spontaneously occurring somewhere in the universe, sometime from its beginning to its end, even if we limit ourselves to carbon-based life. To me, it’s a safe assumption that life of some sort is inevitable in the universe – there’s a lot of universe. If those incalcuable odds are different, I could be wrong, and life may well not be inevitable. It may be incredibly unlikely. Let’s look at a different part of the argument, the most fundamental:

Even if life of any kind is incredibly unlikely, why does that demand special explanation? There are innumerable things in the universe that are incredibly unlikely. It’s incredibly unlikely that the third neutron from the left of the exact centre of Alpha Centauri is moving in the direction it is. Why does this particular phenomenon – life – demand special explanation when nothing else does?

I haven’t got all the way to the bottom of the post yet, but dealing with unlikely things made me think of one of the Science of the Discworld books (my, Pratchett seems to be coming up a lot) from which I took the point that:

The fact that something that is – in itself – wildly improbable happens (they were talking about coincidences) isn’t all that amazing; it’s reasonably likely something else equally improbable would happen the next day.

Considering the number of events that happen even to one person, it’s not surprising some of them are unbelievably unlikely, especially when you also describe them so as to emphasise their improbability.

Correct, Lyndon. It’s just that we happen to put special emphasis on unlikely occurrences involving us – like us existing.

And, Paul, so even if a supernatural explanation was correct, there would be no scope for science to detect it? And are there some things that aren’t testable, and so science has to stay silent on? Like, you mentioned aliens – that sort of thing?

I’ll jump in there at the risk of Paul coming back, calling me foolish and providing a much better answer…

Yes science would have nothing to say about a truly supernatural cause in the universe because it simply wouldn’t be science. If we define the supernatural as something that is not measurable in the natural world (defining the supernatural is not a trivial problem btw) then there is no way science could detect it.

But even if we did somehow know that some unmeasurable force breathed life into dust and made all of Creation it wouldn’t get us anywhere scientifically. Since all supernatural causes are indistinguishable to the methods science we can’t make generalisations or predictions from the observation. If we can’t do that then our knowledge doesn’t get us any closer to understanding the natural world and we are not doing science.

David…I think you are wrong in your analysis of the “supernatural” question, and I think it is because your definition is too narrow.

You say “If we define the supernatural as something that is not measurable in the natural world…”

If God were to appear in the clouds one afternoon over Auckland, and speak to the entire city, the event is measurable thus: He can be seen (natural. He can be heard (natural). He can be photographed or videotaped (natural). Are you suggesting such an event would therefore be “natural” because it could be measured in some form? Are you denying it would be supernatural? Are you denying that a supernatural event could manifest itself in the natural?

If the God in the clouds announced himself as creator of the world, that he did it in six days, and that Adam and Eve were the first people, should science ignore his (recorded, naturally) testimony to this effect, and continue to look for an explanation that doesn’t feature God? Or would that simply become Quioxtic?

I’m not quite sure what you are digging at there. There are predictive hypotheses to be found in the study of these things.

If look around the universe and say “oh look, everything is redshifted” you can develop the hypothesis that this is due to the universe as we know it having arisen from something like a big bang. You can then make the prediction (once you know a little particle physics) that if this event occurred we should be able to detect background radiation from that event bombarding the earth from all quarters.

For abiogenesis we might make the observation that RNA is much more likely to come about than DNA so may have been a precursor to DNA-protein life. Then we can make the prediction that if there was an RNA world then RNA must be able to autocatalyse or that we could evolve chemically active RNA structures in vitro.

And Ryan, where I think you and Lyndon are being sidetracked a little is regarding the probability math. We’re not talking here about odds like those of winning lotto…we are talking odds that leading atheist scientists concede are so big that it wouldn’t matter if the universe was quadrillions of years old, there still isn’t enough time for the event to be even remotely likely.

Well, that’s sort of what I meant about defining the supernatural. I think few of atheists would actually stick our heads in the sand if such a hypothetical event occurred. (I do sort of think it’s a point in our column that these things don’ t happen and I’d also be a bit peeved that this God bloke planted billions of years of geology and evolution just to trick everyone but that’s an aside). Such an event would have effects on the natural world and would therefore be amendable to study.

I guess the point of your question is what would happen if we had perfect knowledge that there was some supernatural force involved making life, the universe and all that. I would think we should do exactly what the thousands upon thousands of very good scientists who are theists do and continue to apply methodological naturalism – the necessary limitation of science to natural explanations – while we do science because that’s the only method with which we can learn about the natural world. If you believe that Blind Io (to keep a theme running) creates thunderbolts that’s fine but, at least in the natural world, you have to believe that he does but separating electrostatic charges in clouds and the like.

Interestingly enough we don’t have a very complete understanding of how thunder and lightening form, perhaps and avenue for a Druidical anti-science movement to arise?

Ryan…you have a major Achilles Heel that you are continuing to offer up as a novel argument even though it has been soundly thrashed by the scientists I'm quoting in The Divinity Code.You say:"However, when you were talking about how complex life is, you were talking about how complex life is today, not how complex the hypotheical self-replicating precursors were."Why is this your Achilles Heel? Because you are appealing to the ignorance of your audience who may not know any differently, and not acknowledging that this very argument was already raised and dealt with in the book.Here's what Shapiro says (page 42):"“Many chemists, confronted with these difficulties, have fled the RNA-first hypothesis as if it were a building on fire. One group, however, still captured by the vision of the self-copying molecule, has opted for an exit that leads to similar hazards."Just for the absolute avoidance of doubt, Ryan, you are in that group of self-replicating molecule enthusiasts. He's talking about you. :)"In these revised theories, a simpler replicator arose first and governed life in a “pre-RNA world.” Variations have been proposed in which the bases, the sugar or the entire backbone of RNA have been replaced by simpler substances, more accessible to prebiotic syntheses."Which is exactly the line you are running. He continues:"Presumably, this first replicator would also have the catalytic capabilities of RNA. Because no trace of this hypothetical primal replicator and catalyst has been recognized so far in modern biology, RNA must have completely taken over all of its functions at some point following its emergence.“Further, the spontaneous appearance of any such replicator without the assistance of a chemist faces implausibilities that dwarf those involved in the preparation of a mere nucleotide soup,” warns Shapiro.“The chances for the spontaneous assembly of a replicator in [such a nucleotide soup] can be compared to those of [a] gorilla composing, in English, a coherent recipe for the preparation of chili con carne."Don't just take Shapiro's word for it (or Harold Morowitz). Francis Crick was working on a basis of 200 million years of evolution before the first DNA lifeform appeared, and at page 40 he is quoted as saying even that was nowhere near enough time to go from precursor to DNA naturally. Hence his belief in spacemen.Are we going to keep dancing around this, or are you prepared to concede that atheistic scientists have already considered and dismissed your line of argument?

I know we’re not, but one of those statistics that you have pulled out in these discussions is the chances of an entire simple cell spontaneously forming. And then you compare those odds to the number of planets estimated to be in the universe.

Firstly, no one is seriously suggesting that a complete cell spontaneously formed. Most are suggesting molecular evolution as a precursor to cellular life.

Secondly, to compare any odds to the number of planets in the universe and point out how overwhelmingly large the odds are compared to the planets is disingenuous. For that comparison to make sense, each planet would be given a single chance to form the pattern and is discarded if it does not. There are billions of reactions occurring every second on each planet, let alone throughout the universe, let alone throughout the temporal span of the universe as well as the spatial span.

And, as I’ve pointed out, we don’t have a comprehensive list of every possible self-replicating molecule there could be, so even trying to determine the odds of the ones we do know spontaneously occurring is won’t be an accurate portrayal of the odds of a self-replicating pattern occuring somewhere.

You list all these odds, but they mean nothing without further information of how they were arrived at and what their scopes are. The odds of me flipping five heads in a row are 1 in 32, but if I flip coins for a solid day, I’m going to flip five heads in a row a bunch of times. It’s very unlikely to occur in a minute, and practically inevitable in a day.

In order to authoritatively say that life is practically impossible, you have to know all the possible self-replicating molecules, the circumstances under which each might form, the quantity of those circumstances throughout the temporal and spatial span of the universe, the number of reactions occurring within those circumstances per second, and the odds that any one of those reactions will form a stable self-replicating molecule.

Ryan…the odds are not mine…they are arguments raised by people like Morowitz, Shapiro, Hoyle and others.

I’m absolutely certain that these people and various Nobel Laureates who’ve used the same data are not so stupid as to have failed to consider the kind of argument you raise.

Shapiro, for example, not only pours scorn on the cell coming together, but also on DNA evolving, and on the RNA world hypothesis and on any pre-RNA precursor. He has the credentials to make these kind of statements…I only report them.

A crystalline structure, at its most complex, is a self-replicating molecular structure, but it is not “alive” under any meaningful definition. It’s growth is purely the result of the laws of physics and chemistry.

Interestingly Ryan, you raise the issue, what’s so special about life as we know it, as opposed to the existence of rocks or whatever…they are all the product of chemical reactions. Wellllll, yes and no. Organic reactions are far, far more complex than those that created rocks, diamonds, salt etc. That complexity is at the heart of what we are actually arguing about.

And organic life reactions are apparently so complex that human engineers cannot replicate them, let alone the random forces of sun, sea and wind that are alleged to have pulled it off.

The specialness, at a scientific level, comes not from the metaphysical aspect of life, but from the sheer bioengineering complexity.

Underlining my argument yesterday that the ingredients for life appear to be universal (because of the nature of the atomic table), I see this story today on key compounds being found in a distant galaxy: http://www.physorg.com/news119633614.html

The ingredients for life to arise (under the increasingly discredited nucleotide soup theory) are absolutely plentiful on earth, too, but scientists can’t get them to self assemble no matter how hard they try, and as I point out some of the best brains in the field have basically written it off and are poking fun at all the young post-grads still trying to publish papers in support of RNA world or nucleotide soup.

So Ryan, when you raise the nebulous claim that “you have to know all the possible self-replicating molecules, the circumstances under which each might form, the quantity of those circumstances throughout the temporal and spatial span of the universe, the number of reactions occurring within those circumstances per second, and the odds that any one of those reactions will form a stable self-replicating molecule..” you are clutching at straws.

We don’t really have to know all that. Because most of it is irrelevant.

We know the coldest temperature in the universe is absolute zero. We know the working temperature range of all stars and planetary systems. We know the behaviour of all atomic elements at given temperatures. We know what elements they are likely to bond or react with. We have synthesised a wide range of bondings that don’t occur in nature, just to see for ourselves what happens.

Nothing magical happens once you leave Earth. It doesn’t matter where you go in the universe, the rules applying to carbon or silicon here will equally apply there.

You have attempted to construct a bolt-hole that doesn’t actually exist: the airy fairy idea that things happen significantly differently elsewhere.

David, you and I would agree that science is the study of natural phenomena. Even if God were to appear in the clouds, scientists would still have a valid role in unravelling the secrets of the natural universe. We don’t disagree on this.

Again, you know perfectly well that the complexity of life as it is now and those things you claim are “so complex that human engineers can’t replicate them” are the result of millions of years of evolution – increasing complexity – and are not the kind of things anyone is claiming were spontaneously “pulled off” by “random forces of sun, sea and wind”. You know that. No one is saying that modern complex life appeared overnight, yet you make objections that would only make sense if you sincerely believed that “modern complex life appeared overnight” is the assertion with which you’re contending.

You say that scientists can’t get the ingredients of life to assemble, and that this is evidence that it didn’t happen by natural processes.

Firstly, self-catalysing molecules have indeed been created in laboratory conditions. Secondly, we’re talking about a hypothesis that involves millions of years of chaotic interaction to get things just right, and we don’t even know for sure what that first self-replicating pattern was. We can never know for certain.

And finally, a growing crystalline structure does not fit the definition of life I gave, that’s correct. But when you’re you talking about the complexity of organic reactions, are you talking about the ones that are the result of millions of years of evolution, or those first self-replicating molecules? What is this added factor about this kind of chemical reaction that you think demands more special explanation than any other chemical reaction?

Also, could you provide a reference (or a page number in DC) for where you get the probabilities from. Because I know you’ve quoted Borel’s odds while talking to me in the past. Is there anyone else’s I should know about?

Because your certainty that scientists would take into consideration all of the objections I’ve raised to the odds may be misplaced.

“Again, you know perfectly well that the complexity of life as it is now and those things you claim are “so complex that human engineers can’t replicate them” are the result of millions of years of evolution…”

“… – increasing complexity – and are not the kind of things anyone is claiming were spontaneously “pulled off” by “random forces of sun, sea and wind”. You know that. No one is saying that modern complex life appeared overnight, yet you make objections that would only make sense if you sincerely believed that “modern complex life appeared overnight” is the assertion with which you’re contending.”

Actually, Ryan, the first known cell appeared, IIRC, about a hundred million years after Earth cooled down enough for rocks to solidify. In other words, the blink of an evolutionary eye. That is PRECISELY the reason Crick didn’t believe life arose naturally – not enough time to evolve such complexity – and that it must have been placed here by aliens.

The odds used in the book are sourced in either the text or footnotes, as I recall…they are well established scientifically – not controversial.

David put it better than I could have done. As for the aliens, which I didn’t mention, if they were corporeal then we could perform autopsies on them at Area 51. If they were ethereal, we might just have to listen to their wisdom.

However, when you were talking about how complex life is, you were talking about how complex life is today, not how complex the hypotheical self-replicating precursors were.

And 100 million years is still an awful lot of time. And we still don’t know what those precursors were. And so we don’t know what conditions they would require or how much time is necessary for their advent to become likely or practically inevitable in those conditions.

In other words, we don’t know. We have better ideas today than we had 50 years ago. The jury is still out. We can reserve judgement, but you’d have to be insane to bet that this is the one thing in the universe that doesn’t have a naturalistic explanation.

For one, Crick was pessimistic about the chances of earthly abiogenesis when he was writing in the 70s about the chances of a protein-first model. He acknowledged in the 90s (that’s a largeish PDF) that RNA first models probably obviated the need for kindly aliens.

And what Ryan appears to be saying is that to be meaningful a probability argument needs to apply not the chances that cells, proteins or even RNA arise but to the liklihood the initial conditions – the ur precursors of the system could arise.

I can’t imagine that Shaipro is saying can’t have gone through an RNA world phase(it’s almost universality held that it did)just that the RNA world can’t be the starting point. Instead we need to investigate things like chemical hypercycles might build some of the chemistry we in biological systems and even how selection might have operated directly on chemistry even before self replication (‘survival of the stablest’ perhaps) or how proto metabolisms might produce RNA precursors.

Any theory for the origin of life relies on a mechanism that makes simple things more complex so calculating the complexity of something that’s half way down one road or the other doesn’t really help us

David, yes, I’m aware of Crick’s variances on it, but he gave a 1998 interview which I quote in the book reverting back to his earlier position.

Additionally, I left off the rest of the Shapiro quote (published in 2007, by the way), which reads:

“…With similar considerations in mind Gerald F Joyce of the Scripps Research Institute and Leslie Orgel of the Salk Institute concluded that the spontaneous appearance of RNA chains on the lifeless earth “would have been a near miracle”.

Shapiro then adds:

“I would extend this conclusion to all of the proposed RNA substitutes that I mentioned above.”

So yeah, I don’t think he’s overly impressed at the early RNA precursor theories at all, any more.

â€œThe chances for the spontaneous assembly of a replicator in [such a nucleotide soup] can be compared to those of [a] gorilla composing, in English, a coherent recipe for the preparation of chili con carne.”

Ian. You are quoting this from an article where Shapiro is arguing that abiogenesis happened differently, not that it didn’t happen. He concludes the article by saying that if his hypothesis was confirmed…

…then our expectations of the place of life in the universe would change. A highly implausible start for life, as in the RNA-first scenario, implies a universe in which we are alone. In the words of the late Jacques Monod, “The universe was not pregnant with life nor the biosphere with man. Our number came up in the Monte Carlo game.” The small-molecule alternative, however, is in harmony with the views of biologist Stuart Kauffman: “If this is all true, life is vastly more probable than we have supposed. Not only are we at home in the universe, but we are far more likely to share it with unknown companions.”

Not only is Shapiro (in that very article you’re quoting) saying that abiogenesis is possible, but he is saying that if he is right, there will be plenty of life in the universe. He co-wrote a book about how likely he thinks alien life is.

You can’t quote people saying “it didn’t happen this way” and edit out the last two words of the statement.

I was not saying that RNA chains were the spontaneously arising precursors to life. I was saying that some kind of self-replicator was. So you quote him criticising that particular kind of self-replicator and conveniently ignore that you’re quoting from an article where he’s arguing for a different kind of self-replicator.

What am I supposed to think, Ian? You assure me, just so there’s no doubt at all, that your quote is criticising people like me (who assert some kind of self-replicator), and it turns out that not only is the quote criticising a much more specific assertion, but the quote is from a scientist who is “people like me”.

I actually think the philosophical debate is much more interesting than the science one (especially since I don’t think there are any organic chemists in this thread…).

It seems to me the whole story of origin of life research highlights the differences between science and natural theology as ways of knowing. You look the chance of RNA or relating molecules spontaneously arising and decide it’s impossible and impossible = god. Scientists have looked at it and said, well that’s unlikely, what other mechanisms can get us that level complexity, how can we test these idea…

And the god you’ve squeezed into the gaps of scientific thinking gets increasingly uncomfortable. Though admittedly we’ll never get to The One True Origin of life the idea that we should no regard it as impossible without divine agency is all little odd.

If you read my chapter carefully, you’ll see I address all the issues you raise re Shapiro, including his preferred theory of origins. It is all in the book.

Having said that, if you read his paper carefully, he spends around 90% of his space attacking the very things I report him attacking. As commenters on one of the threads around his article have pointed out, it was largely a stinging attack on establishment scientific views of the origin of life.

His alternative theory is metabolistic evolution, and he doesn’t spend much time on it in his thesis, apart from saying effectively that it must have happened this way because the other explanations have all failed.

On paper, it appears plausible (as many things do, on paper).Even so, he acknowledges the evidence in support of ME is not there yet either, and experiments so far have failed to fire.

More to the point, you’ll find he also acknowledges that there’s not a skerrick of evidence that such an evolutionary pathway, if it rang again, would lead to DNA. And if RNA/DNA did emerge through this mechanism, then you can add one more incredibly unlikely cosmic accident to the probability equation.

In The Divinity Code, I do address this aspect by saying, well, if he’s right and there is a much simpler pathway to life (which he himself admits is unproven at present), then why are we not seeing non-DNA life forms on planet earth? Why DNA and ONLY DNA?

Why, if simple precursors and small molecule systems make the creation of life almost a given, is there not one organism on this planet that has been generated from such a system?

Like I said previously, there is a huge biosphere with immeasurable niches for life forms to occupy, and up to 100 million species occupying them.

The flaw in the ME/small molecule theory is glaring: if it is so easy, where are they? If it is so easy, why is it not happening in the lab either with the assistance of chemists?

Let’s just be clear. I was talking about any kind of self-replicating pattern, RNA or not, and you quoted Shapiro criticising RNA in an article where he backed a different kind of self-replicating pattern.

You ask why we don’t see non-DNA life arising.

1. If life on earth began with precursors to DNA life, that doesn’t mean it’s an everyday occurence. It doesn’t have to be something that happens each night in your kitchen sink in order to be something that happens fairly regularly (as Shapiro asserts) on an astronomical scale.

2. If some alternative to DNA life were to arise spontaneously, akin to the hypothetical precursor patterns, it would be immediately outcompeted for resources by DNA life, which has had millions of years of evolution to be better at it than any spontaneously arising newcomer. You say so yourself – up to 100 million species of DNA life are already occupying all the resources on earth. There’s no room at this inn.

Surely that’s not your actual objection to Shapiro: “If life started with precursor non-DNA life, we should see it pop up all the time; and we don’t, so it didn’t.”